Electron discharge device with resonator



July 22, 1958 G. DIEMER 2,8

ELECTRON DISCHARGE DEVICE WITH RESONATOR Filed Dec. 11, 1951 4 Sheets-Sheet 1 il' -I'NVENTOR sssmus DI EMER I a I (BY),

AGENT JulyZZ, 1958 a. DIEMER 2,844,756

ELECTRON DISCHARGE DEVICE WITH RESONATOR Filed Dec. 11, 1951 v 4 Sheets-Sheet 2 INVENTOR GESINUS DIEMER July 22, 1958 G. DIEMER 2,344,756

ELECTRON DISCHARGE DEVICE WITH RESONATOR Filed Dec. 11, 1951 ,4 Sheets-Sheet 3' INVENTOR GESINUS DIEMER BY %%W AGENT July 22, 1958 G. DlEMER 2,344,756

ELECTRON DISCHARGE DEVICE WITH RESONATOR FiledDec. 11, 1951 v 4 Sheets-Sheet 4 *JJNVENTOR GESINUS DIEMER AGENT United States Patent ELECTRON DISCHARGE DEVICE WITH RESONATOR Gesinus Diemer, Eindhoven, Netherlands, assignor, by

mesne assignments, to North American Philips Company, Inc., New York, N. Y., a corporation of Delaware Application December 11, 1951, Serial No. 261,102

Claims priority, application Netherlands December 29, 1950 11 Claims. (Cl. 3155.49)

This invention is concerned with devices comprising an electric discharge tube for producing, amplifying or modulating millimeter waves, that is to say waves whose wave-length ranges between a centimeter and several tenths of a millimeter.

Although resonator cavity magnetrons and klystrons permit of producing waves below a centimeter wave length the output or efliciency respectively thus obtained is not such that their use on a large scale is attractive. In addition, the manufacture of such tubes is most diflicult, since the resonator system, which has small dimensions in all directions, must be manufactured with great accuracy. The invention provides a tube for use in a device as referred to hereinbefore, the resonator system being built up in a simple manner and being readily adapted to vari- OHS USGS.

v anelectron beam moving past them so that a potential antinode is formed between two successive wires in the center and potential nodes are formed at theends. The optimum mode of oscillation is that in which successive wires oscillate in phase opposition, that is, have phase opposition of their potentials.

In such devices, the electron beam may move parallel to the plane of the frame and at right angles to the direction of the wires, all the wires being consequently passed by in succession. As an alternative, the electrons travel at right angles to the direction of the frame, the beam striking only one or more wires at the same time and being moved by a suitable device backwards and forwards over the frame at right angles to the direction of the wires. In the first case, the velocity of the electrons parallel to the frame must be such that the electrons traverse the central spacing between two successive wires in a half-period of the-oscillation under consideration. In the second case, the point of impingement of the electron beam on the wires is required to shift with such a speed that the distance between two adjacent wires is also traversed in a half-period. If the velocity of the beam or the speed of deflection respectively is chosen on these lines, the wires are excited in phase opposition in actual fact.

In order that the wires may oscillate in phase opposition in actual fact, they may be alternately slightly shorter and slightly longer than the mean length. The latter requirement can be satisfied in a simple manner by taking alternately thick and thin Wires and uniting the ends of the thick wires by two strips which are arranged in slightly 2 closer proximity to one another than the long sides of the frame on which the wires are strung.

In order to provide higher energies on millimeter waves, a plurality of frames on which wires are strung may be superposed, the electron beam consequently moving between the rows of wires. The strung frames are preferably superposed so that in a direction normal to the plane of the frames the wires are arranged in succession.

If also these frames have thick and thin wires alternately wound on them and the apertures in the frames are bevelled so that the wires engage the frame where the aperture is a maximum, a shortening of the thick wires in relation to the thin ones is obtained of its own accord when piling the frames.

The number of frames to be piled cannot be increased without limit, but the spacing between the outermost wires measured at right angles to the direction of the frame must be smaller than the wavelength and preferably not much in excess of half the wavelength. This ensures that all the adjacent wires oscillate in the same phase. It is possible for the length to which the frame or the pile of frames is strung to exceed the wave length of the oscillations under consideration in air, at any rate to be 1 /2 to 2 times as large.

The resulting resonator system thus has in one direction a dimension greater than the wave length and, in contradistinction to the helix of a travelling wave tube, can withstand a high dissipation of energy. In addition, the manufacture does not entail involved processes.

The strung frames may be completed with the use of conductive plates to form a wave guide in which the wires are stretched and the cross-section of which in the direction of length of the wires is equal to half the wave length and is located at right angles to the plane of the frames between the half-wave length and the whole wave length, the direction of length of the frames being in the direction of length of the wave guide.

For practical use the diameter of the stressed wires is required to be less than 0.25 mm. and the spacing between the center lines to be less thanl mm.

The deflection of'an electron beam over astrung frame may be effected, for example, by modulating the velocity of an electron beam with the use of a cavity resonator in the centimeter wave'band. If the beam is then passed through a constant magnetic field which is at right angles to the direction of travel, the lateral deflection of the beam varies in accordance with the velocity modulation. By causing this beam to brush past the wound frame, the latter can be excited, frequency multiplication being thus achieved. 1

A device according to the invention may alternatively comprise a flat magnetron, a flat electrode being arranged opposite a wound frame and parallel thereto. A recess in the said flat electrode close to the end of the wound frame accommodates an incandescent cathode whose direction of length is parallel to that of the wires. A magnetic field parallel to the direction of the wires is developed and is powerful enough to cause the electrons, at a suitable voltage between cathode and anode, to describe cycloid-like paths, brushing close past the wires and repeating this several times beforebeing collected As an alternative, the plate-shaped electrode may be secondaryemitting, impinging electrons releasing new .ones. i If desired, the entire plate, but devoid of any recess,'may function as a primary cathode.

In this case the mean speed of propagation of the electrons may be such that in a half-cycle of the natural oscil- I I 3 In order that the invention may be readily carried into effect, a number of examples will now be described in detail with reference to the accompanying drawings, in

V which:

Figs. 1 and 2 are two sectional views of the electrode system of an electric discharge tube for use in a device according to the'invention, the resonator system being constituted by a single wound frame;

Fig. 3 shows an electrode arrangement for achieving frequency multiplication by deflection;

Figs. 4, 5 'and 6 are three sectional views of a more elaborate example of a tube for use in producing millimeter waves;

Fig. 7 shows a device according to the invention, in which the coupling-in and coupling-out is effected with the use of Wave guides which are connected to a wave guide in which a wound frame is incorporated and Fig. 8 shows a flat magnetron according to the invention.

In Fig. 1, the reference number 1 designates an incandescent cathode which is adapted to produce a flat electron beam with the use of two small beam-forming plates 2, said beam being directed with the use of a. magnetic field in a longitudinal direction towards a collecting anode 3. The beam travels past a molybdenum frame 7 placed on the thick wires so that the free length of the latter is smaller than that of the thin wires. This enables two adjacent wires always to oscillate in phase opposition. The velocity of the electron beam is chosen to be such that the space between the centre lines of two adjacent wires is traversed in a half-period, it being necessary for tubes of high output that the spacing between the wires at the end should be smaller than that at the beginning, because in this case the electrons have already given off energy to the high frequency field in the same manner as the pitch of the helix in a travelling wave tube is made smaller at the end.

If the device is used as a generator, the energy can essentially be abstracted with the use of a coupling loop 8, and if the device is used as an amplifier the supply of energy can be effected with the use of a coupling loop 9.

Referring to Fig. 3, the reference number 10 designates an elongated cathode having a flat front face which is capable of throwing a web-shaped electron beam through the apertures 11 in front and rear walls of a resonator cavity 12. The region circumscribed by the circle 13 encloses a constant magnetic field at right angles to the plane ofthedrawing. The wound frame is designated by like reference numerals as in Figures 1 and 2 and the collecting electrode is designated 14. As in the above embodiments, the relative spacing between adjacent wires is chosen so as to be traversed by the beam in a half-period of the frequency to be produced. At the points of reversal the distance must be very small and for this reason the beam is collected at these points at the end of the frame.

Referring to Figs. 4, 5 and 6, the reference numeral 15 designates a cylindrical glass bulb in which is arranged a rectangular case 16 having a circular flange 17. Arranged inside the rectangular case 16 are seven elongated frames 18, on which are alternately strung thick and thin wires 19 and 20. The most right-hand frame in Fig. 6 is not wound. The elongated apertures in the frames are bevelled so that the thick wires are given a smaller free length than the thin wires by the next following frame on top thereof. Since the wires are secured in position on the frames with the use of gold solder the frames, after piling, can be interconnected by simple after-heating to form a solid unit, it being necessary to take care to see that the wires shadow one another in the direction normal to the plane of the frames. Also these wires are under appreciable stress. Arranged within the widened end of the plates 18 with the use of two mica plates 21 are a flat cathode 22 on stay rods 23 and also two stay rods 24 which have the rigid grid wires 25 arranged on them. Grid and cathode are connected with the, use of flexible wires to a number of leading-through studs in the tube bottom. For this purpose the sides of the case 16 are partly omitted at 26. Arranged between the wound frames 18 and the case 16 are in addition four conductive strips 29 so that the wires are stretched in a wave guide of rectangular cross-section, the smallest dimension of which is equal to half the wavelength. The maximum dimension ranges between the half-wavelength and the whole wavelength. The end pieces 30 of the wound frames, measured at right angles to the wires, are a quarter wavelength in length so that a transformer is formed between the tube and the outlet formed by the wave guide 27, which is provided with a particular flange 28 to prevent energy from leaking away. The short sides 30 of the frames 13 are a quarter wavelength long in the direction of propagation of the waves and thus jointly with the side walls 26, constitute transformers for the energy to the outlet. The plates 18 are 0.5 mm. thick and the thick and thin wires are and 130 microns respectively. The wound length of the frames 18 is about 12 mms. and the pitch of the Wires is 0.32 mm., the length of the wires is about 12mms. and the pitch of the wires is 0.32 mm., the length of the wires is about 4 mms. on the understanding that the bevelling in the plates 18 is such that the free length of the thick wires at both ends is about 0.1 mm. less than that of the thin wires. The wavelength required to be produced with the use of this tube is about 8 mms. The distance of the wires of the grid which are microns in thickness relative to the cathode is 300 microns and these wires are arranged in the shadow of the wires strung on the frames. The distance of the control grid relative to the first wires on the frames is 630 microns. The cathode is given a voltage of l600 volts in relation to the frames and the voltage of the grid is still slightly negative in relation to the cathode so that the combined action of this grid and the first wires on the frames results in the formation of a number of weblike electron beams which are passed between the frames with the use of a magnet field. The tube is shown about ten times its full size. Although the tube is shown to form a generator, it may be used as an amplifier if a coupling device, for example an aperture in the wave guide or a loop, is arranged in the neighbourhood of the cathode. Oscillating may be counteracted in known manner by providing dampings. Obviously, particular structural difficulty does not arise if a housing of similar construction of about one tenth of the wavelength, and hence from 0.5 to 1 mm, must be realised.

Referring to Fig. 7, the reference numeral 1 again designates the cathode which produces a web-shaped beam with the use of two small beam plates 2, and a collecting anode 3, the frame being designated 4 and the thick and thin wires being designated 5 and 6 respectively, a strip 7 uniting the thick wires. The frame is arranged parallel to the direction of length of a wave guide 31 which at the ends is connected to wave guides 32 and 33 directed in a direction transverse thereto and connected to the first-mentioned wave guide by apertures 34. and 35. The electron beam travels through the apertures 36 and 37. If the device is used as an ampii fier, the supply and discharge of energy is effected by the wave guides 32 and 33 respectively.

Referring to Fig. 8, the wound frame with wires and strip are designated by the same reference numerals as in Figures 1, 2, 3 and 7. Arranged parallel to the frame is a flat electrode 38 which has a recess 39 formed in it. This recess accommodates a filamentary incandescent cathode 40, a cross 41 designating the direction of the magnet field developed between the electrodes and parallel to the wires. The electrode 38 is given cathode potential. As an alternative, a strung frame may be arranged, jointly with the other electrode, in a wave guide, the direction of propagation of the waves being at right angles to the Wires and parallel to the frame.

What I claim is:

1. An electrical device adapted for operation in the extremely-high-frequency range, comprising a resonator body, said resonator comprising a planar conductive frame member and a plurality of conductive taut wires mounted on and across said frame member, opposite ends of each of said wires being secured to and in electrical engagement with opposite sides of said conductive frame member, said wires being substantially parallel to one another and lying substantially in a single plane and being spaced apart from one another a distance small relative to their length, said wires each having a length approximately equal to one-half of a wavelength of the operating frequency of said device, means for projecting an electron beam close to and past said resonator in a direction substantially parallel to the plane of said wires and substantially normal to the length direction of said wires whereby the electrons in the beam traverse the space between successive wires in the time of about a half-period of said operating frequency to eifect interaction between said beam and said wires and thereby cause successive wires of said resonator to oscillate in phase opposition, and means coupled to said resonator for abstracting high frequency energy therefrom.

2. An electrical device as set forth in claim 1 wherein the wires of the resonator constitute two groups of alternately-arranged wires, with wires of one group interposed between wires of the other group, the wires in one of said groups having a length slightly smaller than about one-half of a wavelength ofthe operating frequency, the wires of the other group having a length slightly larger than about one-half of a Wavelength of the operating frequency.

3. An electrical device as set forth in claim 2 wherein the wires in one group are thicker than the wires in the other group, a conductive member being placed in engagement with the ends of the thicker wires only whereby the latter are eifectively made shorter than the thinner wires.

4. An electrical device as set forth in claim 2 wherein the resonator comprises a plurality of said wound frame members mounted in abutting relationship.

5. An electrical device as set forth in claim 1 wherein the wires are each constituted of a material selected from the group consisting of tungsten and molybdenum.

6. An electrical device as set forth in claim 5 wherein the diameter of each of the wires is less than 0.25 mm. and the spacing between the axes of successive Wires is less than 1.0 mm.

7. An electrical device adapted for operation in the extremely-high-frequency range, comprising a resonator body, said resonator comprising a plurality of stacked,

.of the other group, the wires in one of said groups having a length slightly smaller than about one-half of a wavelength of the operating frequency, the Wires of the other group having a length slightly larger than about one-half of a wavelength of the operating frequency, means at one end of said stacked frames for projecting an electron beam therethrough and-close to and past each of said frames in a direction substantially parallel to the plane of said wires and substantially normal to the length direction of said wires whereby the electrons in the beam traverse the space between successive wires in the time of about a half-period of said operating frequency to effect interaction between said beam and said wires and thereby cause successive wires on each of said frames to oscillate in phase opposition, and means coupled to the other end of said stacked frames for abstracting high frequency energy therefrom.

8. An electrical device as set forth in claim 7 wherein the spacing between the wires on the frames at opposite sides of the stack is smaller than a Wavelength of the operating frequency.

9. An electrical device as set forth in claim 8 wherein wave guide means are provided surrounding the stacked frames, whereby the direction of' propagation in said waveguide means is parallel to the planes of the wires and 'at right angles to their length direction.

10. An electrical device as set forth in claim 9 wherein signal input means are coupled to the end of the stacked frames adjacent the beam projecting means.

11. An electrical device as set forth in claim 7 wherein the frames include a bevelled aperture, the wires in one group are thicker than the Wires in the other group, and the frames contact the thicker wires on adjacent frames so that they are made slightly shorter than the thinner wires.

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